What Is a Mainframe and How Does It Work?

What Is a Mainframe and How Does It Work?


Since the 1960s, the mainframe has been the world’s most popular platform for business applications. This made it an ideal candidate for networking. In this article, you will learn some basic information about mainframes and their networking environment to understand how they can be used in a distributed computing environment.

A Mainframe is a large-capacity computer system with many memory (RAM) and processors. Mainframe data servers are designed to process billions of simple calculations and transactions in real time with high security and reliability.

Mainframes were produced by vendors like IBM, Unisys, Hitachi, Bull, Fujitsu, and NEC. IBM was the largest vendor – it has a 90% market share in the mainframe market. The latest IBM z13 mainframe launched in 2015 can host up to 10TB of memory and 141 processors, running at the speed of 5GHz.

Who uses Mainframe Networks?

Mainframes are generally used by large organizations that need powerful machines with high processing power. Sectors such as banking and finance use mainframe computers for making secured transactions.

Today, Mainframes are responsible for anything from simple cash withdrawals from an ATM to airline reservations. Mainframe provides the e-commerce and mobile world with a reliable, available, and scalable way to perform their basic business functions.

Read More: How can eSim Simplify Management and Security in IoT Devices?

How does a Mainframe-based network work?

The Mainframe can work as separate virtual machines located in one place. The resources in the Mainframe are separated into one or more different virtual systems to process the data. This increases the security as even if one system gets affected, it doesn’t impact others. At the same time, data can be stored in one place and can be transferred if needed. Mainframes are mostly used as servers to manage large data. If we try to join thousands of small servers, they cannot handle the amount of data dealt with by a single mainframe with the same reliability and security.


Mainframe Architecture

A mainframe architecture consists of processing units (PUs), memory, I/O channels, control units, and devices. The architecture of a mainframe is illustrated below.


The various parts of the architecture are explained below.

  • Processing units:The mainframe consists of multiple Processing Units (PUs) and no central processing unit exists. The total of all processing units in a frame is called Central Processor Complex (CPC).The CPC has its cage inside the mainframe and consists of one to four so-called book packages. This book package includes processors, memory, and I/O connections like x86 system boards.
  • Main Storage:The book package in the CPC cage contains from four to eight memory cards. One of the fully loaded z9 mainframes has four book packages that can provide up to 512 GB of memory.
  • Channels, ESCON, and FICON:A channel provides a data and control path between I/O devices (Smaller PUs built with specific architecture to take input and compute an output) and memory. Different slots in the I/O cages are reserved for different types of channels and connections, this is explained as below:
    1. Open Systems Adapter (OSA): OSA adapter provides connectivity to various industry-standard networking technologies, including Ethernet
    2. Fibre Connection (FICON): FICON is the most flexible channel technology. With FICON, I/O devices can be located many kilometres from the mainframe to which they are attached.
    3. Enterprise Systems Connection (ESCON): ESCON is an earlier type of fibre-optic technology. ESCON channels can provide fast performance compared to FICON channels, but these channels are limited to shorter distances.

Control units:

A control unit contains logic to work with a particular type of I/O device, like a printer or a tape drive. It is similar to an expansion card in an x86 or midrange system.

Advantages of Mainframe Computers

  • Powerful operating system- Mainframe uses operating systems such as VM, MVS, and z/OS to take advantage of the advanced technology in mainframe hardware which helps produce the level of throughput which makes mainframes attractive to large companies.
  • Security- one of the most important advantages of using a mainframe is providing high security and data protection. Large-scale organizations such as banks and finance companies use mainframe computers to maintain their confidential information.
  • Scalability- The mainframe computer can support extra big power processors. It can be expanded by adding multiple ultra-power processors, memory, and storage device when required to process huge data concurrently.
  • Reliability- Modern mainframe computer systems are capable to run frequently for 40 to 50 years without getting any errors and provide zero downtime.
  • Compatibility- These computers come with their own operating system that supports a wide range of hardware and software. Also, mainframe computers do not restrict the number of operating systems to functioning as only one.

Disadvantages of Mainframe Computers

  • High cost- The mainframe computer’s cost is very high compared to regular computers. The hardware and the software used in the mainframe computer make it expensive. Generally, big organization uses mainframe computers to fulfill their advanced requirements.
  • Installation- The mainframe computer system requires more space and less temperature. Also, these computers require a separate operating system different from a regular one.
  • Maintenance- It required trained staff for the handling of the mainframe computers. The entire system can get down due to major damage to the hardware component’s system.